The Thomas More Law Center filed the suit on behalf of Brenda Brinsdon alleging the McAllen Independent School District violated the 15-year-old girl’s constitutional rights when she was forced to recite the Mexican pledge and sing the Mexican national anthem.

Brinsdon, who is the daughter of a Mexican immigrant and an American father, refused. She believed it was un-American to pledge a loyalty oath to another country.

Ironically, the school district has a policy that prohibits a school from compelling students to recite the American Pledge of Allegiance.

The district also has a written policy that excuses students from reciting text from the Declaration of Independence if the student “as determined by the district, has a conscientious objection to the recitation.”

“There is a sad trend in public schools across our nation to undermine American patriotism,” said Richard Thompson president of the Thomas More Law Center. “But it’s encouraging to see students like Brenda stand up for America despite pressure from school officials.”

The TMLC told Fox News the district ignored its own rules when Brinsdon refused to recite the pledge of a foreign country.

What’s most troubling is the different treatment for someone wanting to opt out of reciting the American Pledge of Allegiance compared to someone as a matter of conscience wants to opt out of reciting the Mexican pledge,” spokesman Erin Mersino told Fox News.

A spokesman for the McAllen Independent School District told Fox News they had not seen a copy of the lawsuit.

The recitation of the Mexican pledge and the singing of the Mexican national anthem was part of a 2011 Spanish class assignment at Achieve Early College High School. The teacher, Reyna Santos, required all her students to participate in the lesson.

When Brinsdon refused to back down – she was punished, the lawsuit alleges. She was given an alternative assignment on the Independence of Mexico. The teacher gave her a failing grade – and then required the student to sit in class over a period of several days to listen to other students recite the Mexican flag.

The lawsuit states Brinsdon offered to recite the American pledge in Spanish but the teacher refused her request.

“It’s astonishing that this Texas school would deny Brenda her right of conscience and free speech not to pledge allegiance to a foreign country,” said Thompson. “Too many Americans – including those of Mexican descent – have suffered and died protecting our nation.”

And while she is fluent in Spanish and English and is proud of her Mexican heritage, Brinsdon is a “true-blooded American,” Mersino added.

Mersino said it was especially troubling to watch video of students in the class standing up, extending their arms straight out, palms down and reciting the pledge of a foreign country.